Optical proximity sensors, such as the AVAGO TECHNOLOGIES™ HSDL-9100 surface-mount proximity sensor, the AVAGO TECHNOLOGIES™ APDS-9101 integrated reflective sensor, the AVAGO TECHNOLOGIES™ APDS-9120 integrated optical proximity sensor, and the AVAGO TECHNOLOGIES™ APDS-9800 integrated ambient light and proximity sensor, are known in the art. Such sensors typically comprise an integrated high efficiency infrared emitter or light source and a corresponding photodiode or light detector, and are employed in a large number of hand-held electronic devices such as mobile phones, Personal Data Assistants (“PDAs”), laptop and portable computers, portable and handheld devices, amusement and vending machines, industrial automation machinery and equipment, contactless switches, sanitary automation machinery and equipment, and the like.
Referring to FIG. 1, there is shown a prior art optical proximity sensor 10 comprising infrared light emitter 16, light emitter driving circuit 51, light detector or photodiode 12, light detector sensing circuit 53, metal housing or shield 18 with apertures 52 and 54, and object to be sensed 60. Light rays 15 emitted by emitter 16 and reflected as light rays 19 from object 60 (which is in relatively close proximity to optical proximity sensor 10) are detected by photodiode 12 and thereby provide an indication that object 60 is close or near to sensor 10.
As further shown in FIG. 1, optical proximity sensor 10 further comprises metal housing or shield 18 formed of metal and comprising apertures 52 and 54 located over light emitter 16 and light detector 12, respectively, such that at least a first portion of light 15 emitted by light emitter 16 passes through aperture 52, and at least a second portion of the first portion 19 of light reflected from object to be detected 60 passes through aperture 54 for detection by light detector 12. As shown, metal housing or shield 18 may further comprise first and second top portions beneath which light emitter 16 and light detector 12 are disposed, respectively. Disposed between and beneath first and second top portions 61 and 63 comprise are optically opaque metal inner sidewalls 25 to provide optical isolation between light emitter 16 and light detector 12.
Many optical proximity sensors generally include a metal shield, such as shield or housing 18 of the type shown in FIG. 1, to provide optical isolation between light emitter 16 and light detector or photodiode 12 so that undesired optical cross-talk between emitter 16 and detector 12 is minimized. See, for example, the Data Sheets corresponding to the AVAGO TECHNOLOGIES™ APDS-9120 Integrated Optical Sensors Preliminary Datasheet and the AVAGO TECHNOLOGIES™ APDS-9800 Integrated Ambient Light and Proximity Sensors Preliminary Datasheet, each of which is hereby incorporated by reference herein, each in its respective entirety.
FIG. 2 shows a prior art optical proximity sensor 10 with a relatively complicated metal shield or housing 18. The optical proximity sensor shown in FIG. 2 is an AVAGO TECHNOLOGIES™ APDS-9800 Integrated Ambient Light and Proximity Sensor, which contains a printed circuit board (“PCB”) or substrate 11 upon which are mounted LED 16, light detector or photodiode 12, and ambient light sensor 14. Two-piece metal shield 18 covers LED 16, light detector or photodiode 12, and ambient light sensor 14 and contains a downwardly projecting light barrier 25 disposed therebetween. In the APDS-9800 optical proximity sensor, metal shield 18, being of a considerably complicated shape and geometry, is formed and thinned using progressive metal stamping techniques, and must be hand-fitted and attached to the underlying PCB by gluing to ensure proper alignment and fit.
Note that APDS-9800 sensor 10 of FIG. 2 does not include any lenses disposed over light emitter 16, light detector 12, or ambient light sensor 16. As discussed in more detail below, it has been discovered that the lack of collimating lenses on devices such as the APDS-9800 sensor results in substantial performance losses, as some light emitted by the sensor is unfocused and subsequently dissipates, and some light emitted by sensor 10 is lost to dispersive effects. Light loss is further exacerbated by windows in portable electronic devices having low optical transmittances or themselves generating unacceptably high levels of crosstalk. All these factors reduce the distance at which objects may be detected by an optical proximity sensor.
As will now be seen, at least some optical proximity sensors of the prior art have metal shields 18 which are difficult or time-consuming to fit. In addition, at least some optical sensors of the prior art exhibit excessive crosstalk and poor optical efficiency, both of which factors reduce the effective distance at which objects may be detected by such sensors. In addition, the commercial marketplace demands ever smaller portable electronic devices. This of course means there exists a motivation to make optical proximity sensors ever smaller.
What is need is an optical proximity sensor design that results in a metal shield that can be accurately and quickly placed on the sensor during the manufacturing process, that exhibits decreased crosstalk and increased detection distance, and that features improved performance, lower cost, increased manufacturability and improved reliability. What is also needed is a smaller optical proximity sensor.